title: The PhtL protein of Pseudomonas syringae pv. phaseolicola NPS3121 affects the expression of both phaseolotoxin cluster (Pht) and Non-Pht encoded genes.
abstract: Pseudomonas syringae pv. phaseolicola, the causal agent of halo blight disease in bean, produces a toxin known as phaseolotoxin, whose synthesis involves the products of some of the genes found within the Pht region. This region, considered a pathogenicity island, comprises 23 genes arranged in five transcriptional units: two single-gene units (argK, phtL) and three arranged as operons (phtA, phtD, phtM), most with unknown function. In P. syringae pv. phaseolicola, maximal expression of most of the genes encoded in the Pht region and the synthesis of phaseolotoxin require the product of the phtL gene, of unknown function but that has been proposed to have a regulatory role. In order to evaluate the role of phtL gene in P. syringae pv. phaseolicola, we performed a comparative transcriptional analysis with the wild type and a phtL(-) mutant strains using microarrays. The microarray data analysis showed that PhtL regulates the expression not only of genes within the Pht region, but also alters the expression of genomic genes outside it, indicating that this gene has been integrated into the regulatory machinery of the bacterium. The expression changes of many of those genes were confirmed by RT-PCR. This study also demonstrated the importance of the PhtL protein in the process of iron response, and suggests that the effect of PhtL on the expression of pathogenicity related, respiration and oxidative stress genes, observed in this study, appears to be indirect through its influence on the Fur protein expression.
authors.affiliation: Departamento de Ingeniería Genética, CINVESTAV-IPN Unidad Irapuato, Apdo Postal 629, CP 36821 Irapuato, Gto, Mexico. Electronic address: luisitin25@hotmail.com.
authors.forename: Luis
authors.initials: L
authors.lastname: González-Villanueva
authors.affiliation: Departamento de Ingeniería Genética, CINVESTAV-IPN Unidad Irapuato, Apdo Postal 629, CP 36821 Irapuato, Gto, Mexico.
authors.forename: Jackeline Lizzeta
authors.initials: JL
authors.lastname: Arvizu-Gómez
authors.affiliation: Universidad Autónoma de San Luis Potosí, Unidad Académica Multidisciplinaria Zona Huasteca, Romualdo del Campo 501, Fraccionamiento Rafael Curiel, C. P. 79060 Cd. Valles, San Luis Potosí, Mexico.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Hernández-Morales
authors.affiliation: Departamento de Ingeniería Genética, CINVESTAV-IPN Unidad Irapuato, Apdo Postal 629, CP 36821 Irapuato, Gto, Mexico.
authors.forename: Selene
authors.initials: S
authors.lastname: Aguilera-Aguirre
authors.affiliation: Departamento de Ingeniería Genética, CINVESTAV-IPN Unidad Irapuato, Apdo Postal 629, CP 36821 Irapuato, Gto, Mexico. Electronic address: aalvarez@ira.cinvestav.mx.
authors.forename: Ariel
authors.initials: A
authors.lastname: Álvarez-Morales
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D044404:Genomic Islands; D008969:Molecular Sequence Data; D005810:Multigene Family; D009952:Ornithine / Q000031:analogs & derivatives* / Q000096:biosynthesis; D044224:Pseudomonas syringae / Q000235:genetics* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; C021234:phaseolotoxin; D009952:Ornithine
keywords: Iron regulation; Microarray assay; Phaseolotoxin; Pseudomomas syringae pv. phaseolicola; Virulence